The invention relates generally to marine engines, and more particularly, to propeller hubs.
Outboard engines include a drive shaft extending from an engine power head, through an exhaust case, and into an engine lower unit. The lower unit includes a gear case, and a propeller shaft extends through the gear case. Forward and reverse gears couple the propeller shaft to the drive shaft. The drive shaft, gears, and propeller shaft sometimes are referred to as a drive train.
A propeller is secured to and rotates with the propeller shaft. Torque from the propeller is transmitted to the shaft. Specifically, propeller hub assemblies transmit torque to the propeller shaft. Exemplary propeller hub assemblies include cross bolts, keys, shear pins, plastic hubs, and compressed rubber hubs.
Such hub assemblies should have sufficient strength or stiffness so that during normal engine operations, very few losses occur between the propeller shaft and the propeller. Such hub assemblies, however, also should be resilient so that the engine drive train is protected in the event of an impact, e.g., if the propeller hits a log or rock. Further, since engine manufacturers often utilize different propeller shaft arrangements, it would be desirable to provide propeller hub assemblies that facilitate use of one propeller on engines of different engine manufacturers.
In an exemplary embodiment, a propeller assembly includes an inner hub, an interchangeable drive sleeve that mates with the inner hub, a biasing member that biases the drive sleeve into contact with the inner hub, and a propeller including an outer hub in which the inner hub and drive sleeve are inserted. More particularly, the inner hub includes a plurality of teeth that mate with a corresponding plurality of drive sleeve teeth.
The drive sleeve includes a first body portion and a second body portion. The second body portion has a larger diameter than the first body portion and includes drive sleeve teeth. A bore extends through the drive sleeve, and a plurality of splines are in an inner diameter surface of the drive sleeve bore. The splines are configured to mate with a plurality of splines on a propeller shaft that extends through the bore.
The inner hub includes a plurality of drive keys that mate with a plurality of grooves in an inner surface of the outer hub. The inner hub teeth are at an end of the inner hub and mate with the drive sleeve teeth. The biasing member contacts the drive sleeve and biases the drive sleeve into contact with the inner hub such that rotation of the inner hub rotates with the drive sleeve.
The outer hub includes a cylindrical shaped body. A plurality of blades extend from an outer diameter surface of the outer hub body. An inner diameter surface of the outer hub body is shaped to mate with the inner hub drive keys to limit relative movement between the inner hub and the outer hub.
During operation, and upon the occurrence of an impact, the drive sleeve compresses the biasing mechanism and the drive sleeve teeth slip with respect to the inner hub teeth. Thus, the propeller shaft and drive sleeve are permitted to rotate with respect to the inner hub and propeller outer hub. The operational condition in which the drive sleeve teeth slip with respect to the inner hub teeth is sometimes referred to herein as the resilient operation mode.
The above described propeller assembly facilitates the easy replacement of the inner hub. Specifically, in the event that the inner hub needs to be replaced, a user simply removes the propeller assembly from the propeller shaft, and removes the drive sleeve and inner hub from within the outer hub. A replacement drive sleeve and/or inner hub can then be utilized when reassembling the propeller assembly and mounting the assembly on the propeller shaft.
Further, different drive sleeves can be provided so that the propeller can be utilized on many different types of marine engines. For example, one particular marine engine may have splines on the propeller shaft of a first length, and another particular marine engine may have splines on a propeller shaft of a second length. Different drive sleeves having different length splines on their inner diameter surfaces can be provided. Although different drive sleeves are utilized, a same propeller can be used. That is, by providing interchangeable drive sleeves, one propeller can be used in conjunction with many different type engines.